Developments in transdermal patches are providing opportunities for smart fabrics which are able to deliver drugs actively to patients, according to Issue No 94 of Technical Textile Markets from the global business information company Textiles Intelligence.
Conventional transdermal patches can only be used to deliver medication which has molecules that are small enough to penetrate the skin. For medications which have molecules that are not able to penetrate skin, delivery can be facilitated by adding an array of microneedles. But it is not possible using conventional transdermal patches or microneedle devices to control the release of the medication or the amount delivered over time.
The use of active drug delivery systems overcomes this limitation. Such systems could take the form of smart fabrics which have the ability to provide patients with individualised treatment. This could be important in the care of chronic health problems which require a patient’s condition to be monitored closely.
For instance, it may be possible to fine tune the delivery of insulin to people with diabetes by using a device containing a carbon nanotube membrane and a feedback sensor which measures blood glucose levels. Using this technique would avoid the problem of potential breakdown in the gastrointestinal tract and some liver problems.
Two researchers at the University of Kentucky have developed a prototype of a transdermal patch which can be programmed to deliver varying doses of medication according to a patient’s needs. The patch is based on a membrane containing billions of carbon nanotubes which are “voltage gated” so that they open and close in order to allow fluid to flow through them at rates that are proportional to an applied electrical current.
NuPathe, a USA-based pharmaceutical company, has developed a single use battery powered transdermal patch, called Zecuity, which employs a transdermal delivery technology that transports medication rapidly through the skin using a non invasive process called iontophoresis.
This process involves the active transportation of molecules by applying a mild electrical current to the skin using two reservoirs. One of the reservoirs contains ionised, or charged, medication while the other contains a counter ion, commonly sodium chloride.
Unlike passive transdermal technologies, which rely on diffusion for the delivery of medication, iontophoresis controls the amount and rate of delivery of the medication.
Hewlett-Packard (HP), a USA-based multinational information technology company, has invented a smart patch based on its inkjet technology which injects precise doses of a drug just under the surface of the skin. The patch is embedded with ultrafine needles through which jets of drugs, rather than ink, are forced. It also contains a computer chip which can administer one or more drugs in various doses and at different times, depending on the needs of the patient.
Individual microneedles can be programmed to administer drugs individually. As a result, in the way that an inkjet cartridge is able to print different colours, the patch can deliver multiple medications.